1. Field of the Invention
The present invention relates to a device for de-icing an external wall of a vehicle.
More particularly, although not exclusively, the de-icing device is, according to the invention, intended to be fitted to the control surfaces, ailerons, flaps, wings, empennages and the like of aircraft, for example airplanes and helicopters.
2. Background Art
This is because, as is known, when aircraft pass, in the course of their use, through regions in which the weather conditions are harsh and unfavorable, ice can form over a relatively long time on these aerodynamic surfaces, and this may consequently cause them to malfunction, with possibly serious consequences for the control of the aircraft. These aerodynamic surfaces are thus fitted with de-icing devices, which may be of the type with an electrical resistor or an inflatable covering.
In the latter case, which is the case to which the invention relates, known de-icing devices include a flexible covering which at least partially covers said surface, and a compressor for inflating said covering. When ice forms on the aerodynamic surface, with the risk of making it difficult or impossible for it to operate, pressurized gas is fed into the covering, via the delivery orifice of the compressor, which may be that of the jet engine. The covering expands, with the result that the layer of ice breaks into a large number of pieces and is then ejected from said surface.
The supply of compressed gas outlet by the compressor is then interrupted, so that the flexible covering deflates and resumes its initial position on the surface, the compressed gas being discharged to the outside through a valve or equivalent. As soon as ice begins to form again, another inflation/deflation cycle is performed.
U.S. Pat. No. 2,883,129 discloses a device of this type, including:
a flexible covering, at least partially covering the external wall of the vehicle; PA1 a compressor; and PA1 a control component where connections, respectively originating from the intake orifice and the delivery orifice of said compressor terminate, said control component inducing either inflation or depressurization of said flexible covering. PA1 said connection connecting said intake orifice to said control component is equipped with an aeration valve with preset calibration, which allows depressurization of said flexible covering and which, when the pressure reduction in said covering reaches a predetermined value, allows outside air to be taken in by said compressor; and PA1 a reservoir for storing pressurized inflation fluid is arranged between said delivery orifice of the compressor and said control component.
With a device of this type, it is thus possible, at the start of an operating cycle, to create a reduced pressure in the flexible covering by directly connecting it to the intake orifice of the compressor, so that the covering is pressed against the aerodynamic surface (external wall), and this may start to break the ice which is being formed. The depressurized covering is then inflated to the predetermined value by connecting it, via the control component, to the delivery orifice of the compressor (the intake orifice no longer being connected to the covering) which, by expansion, causes the ice to break (this having already started during the depressurization) and to be detached from the covering. This depressurization thus plays a part in starting to break the ice, contributing to quicker and more efficient removal of the ice. In addition, establishing a reduced pressure makes it possible to obtain a large absolute pressure range (the difference between the inflation pressure and the pressure reduction), while remaining within acceptable working limits for the covering which contracts and undergoes expansion during an operating cycle of the device.